1. Field of the Invention
This invention relates to an optical apparatus such as a single-lens reflex camera, a still video camera or a video camera which is provided with a visual axis detecting device and designed to start a predetermined control function on the basis of the output of the visual axis detecting device.
2. Related Background Art
As disclosed in Japanese Laid-Open Patent Application No. 3-87818, there is known an apparatus which can select a control function by an observer's visual axis position. By applying such an apparatus to a camera or the like, the setting or the like of photographing conditions can be input by the visual axis.
Also, in the visual axis detecting device described above, a photographer's eyeball is illuminated by an infrared light emitting diode or the like and the image of the eyeball is directed to an image sensor such as a CCD.
Further, it is often the case that display means in the field of view of a finder is illuminated by an LED of high luminance.
Now, generally in the field of view of the finder of a camera, a display portion for displaying photographing information is provided adjacent to an object image observation field, and in case of photographing, attention is always paid to this display portion and an object image, whereby photographing under appropriate conditions becomes possible. Accordingly, it is necessary for the finder observer to see the display portion and the object image alternately, but this often results in the following inconvenience. Human sight is obtained as a result of collectively processing image information projected onto a retina, and image information obtained a moment before is also added and recognized there. In fact, it has been found that the gaze point repeats a considerably vehement jumping exercise and stoppage, and there is a time when the gaze position by the sight and eyeball motion cannot be completely related with each other at one to one.
Accordingly, in spite of the observer being conscious of seeing the display portion, it is detected that actually, the visual axis position lies on an index mark for a predetermined control function started on the basis of the output of the visual axis detecting device, and it may happen that against the observer's will, the camera starts this predetermined function.
Also, U.S. Pat. No. 4,109,145 is known as an eye-controlled apparatus.